Tucked inside every F-chassis M2, M3, and M4 is BMW’s 3.0-liter twin-turbo inline-six, the legendary S55. Producing over 425 horsepower and 400 lb-ft of torque, it’s a powerhouse that’s earned both praise and criticism since its 2014 debut. From owners pushing 600–700 horsepower on stock internals to others experiencing complete engine failure at stock power, the S55 has seen it all, putting it right in the center of controversy.

When discussing the S55, one issue always dominates the conversation: the crank hub. Since the engine’s debut, owners have experienced everything from stock cars suffering crank hub failure under normal driving to heavily modified 600–700 horsepower builds running problem-free for years.

The reality is that the risk exists on every S55, but whether you address it depends on the type of owner you are. Some are willing to roll the dice and deal with it only if it happens, understanding that failure can potentially lead to catastrophic engine damage. Others prefer the peace of mind that comes from addressing it proactively, so they can enjoy the car without the problem constantly on their mind.

At our shop, we strongly recommend the preventative route. To eliminate the factory hub’s weak point, our technicians replace it with a much stronger two-piece crank hub solution that prevents the hub from slipping under load. For us, it’s one of the best upgrades you can make to confidently enjoy the S55 the way it was meant to be driven.